Improved cap raising mechanism for incubators

Abstract: It is well-known to use evaporation caps in an incubator of an analyzer to prevent evaporation of patient sample retained on a test element therein. These caps work well when the test element bearing a patient sample is inserted into the incubator in a particular direction. However, if the orientation of the test element is changed for whatever reason, the patient sample may be disturbed by the evaporation cap. Described herein is an improved evaporation cap (80, 81, 82, 84, 92, 94, 96, 97) which allows a test element to be inserted into the incubator in any orientation. The cap comprises a body portion (81) having opposite ends (82, 84) with a sealing surface (97) located between the ends. Legs (92, 94, 96) depend from each end of the cap and extend through a support on which the caps and covered test elements rest. A camming track mechanism is provided underneath the support which cooperates with the legs (92, 94, 96) to raise and lower both sides of the cap simultaneously to avoid any significant sideways thrust on the cap or on a test element underneath.

Description: This invention relates to incubators used in clinical analyzers, and especially to the evaporation caps used therein and the mechanism for raising and lowering them. Evaporation caps are known for incubator stations on a rotor. Examples are disclosed, for example, in EP-A-0 377 505 and in US-A-4 963 333. In EP-A-0 377 505 an arrangement is described which raises and lowers evaporation caps by having a camming mechanism provided above each cap. In US-A-4 963 333 the caps so disclosed feature camming feet at two of four corners of the cap, and two pivot feet at the other two corners. A recess is provided in the under surfaces to accommodate two upwardly projecting liquid drops on a potentiometric slide element. The cap works by pivoting on its two pivot feed due to the camming feet riding up onto an incoming slide, thus clearing the cap under surface from contact with the upwardly projecting drops. Such a cap works well when the location of the upwardly projecting drops is adjacent the trailing edge of the slide element, such as is the case on the analyzer available from Eastman Kodak Company under the trademark "Ektachem 250", hereinafter the "E-250". It does not work so well, however, if the slide element is turned 180° so that the upwardly projecting drops are adjacent the leading edge of an incoming slide element. The latter occurs when using a slide distributor such as is found in the analyzer disclosed in US-A-4 298 571. Distributors are particularly useful when using more than one incubator, for example, as in the "Ektachem 700"™ analyzer also available from Eastman Kodak Company. That distributor receives the slide in the orientation mentioned for the "E-250", and then turns it 180° for insertion into an incubator. Such a distributor is not used on the E-250. The reason why the 180° reversal of the slide renders the described cap less useful is that the resulting nearness of the projecting drops to the pivot edge of the cap necessitates a larger size of the camming feet which is impractical. However, because a single incubator cannot be made indefinitely large, then such a distributor allows for a higher throughput, using plural incubators, than when it is not used. It would be advantageous to provide a cap which cams upwardly by some mechanism as the potentiometric slide enters with the upwardly-projecting drops adjacent the leading edge. Such camming has to be done with some care, since the upwardly-projecting drops should not be jarred sideways, that is, along the axis connecting them, lest the needed flow of the drops towards each other to form a junction, be disturbed. It is this need that, prior to this invention, has not been achieved inexpensively, by a design allowing ready access to top removal of the caps for cleaning and the like. It is therefore an object of the present invention to provide an incubator and evaporation caps which solve the aforementioned problems and needs. The objects of the invention are achieved by the incubator according to claim 1, and the evaporation cap according to claim 7. Preferred embodiments of the invention are disclosed in the dependent claims 2-6 and 8. Accordingly, it is an advantageous feature of the invention that an incubator is provided with evaporation caps and means for raising and lowering them without any significant sideways thrust, while still allowing easy access to all the caps for removal. For a better understanding of the present invention, reference will now be made, by way of example only, to the accompanying drawings in which:- Figure 1 is an elevational sectioned view of a prior art evaporation cap, showing its disadvantage when the "wrong" edge of the slide element advances under it; Figure 2 is a fragmentary isometric view of an incubator, minus its housing, showing the present invention; Figure 3 is an isometric view of the support used in the present invention, together with a cap at two of the stations; Figure 4 is an isometric view showing the cooperation between the cap and the cam tracks of the invention, the incubator support having been omitted for clarity; Figure 5 is an exploded isometric showing all three of the cap, support and cam tracks together; and Figure 6 is an end elevational view of a cap and cam track, minus the incubator support, of an alternate embodiment of the present invention. The description that follows is of the invention as used in the preferred embodiments, namely in a single analyzer incubator in which potentiometric slide test elements are incubated while being rotated about an axis. In addition, the invention is useful regardless of the other features of the analyzer apart from the incubator or the number of incubators present, and regardless of the type of test element used or the manner in which they are moved through the incubator, so long as the test elements need an evaporation cap. Descriptors such as "above", "below", "underneath" and the like refer to orientations of parts as they are used when in their preferred assembled positions. In Figure 1, an evaporation cap 12 of the type described in US-A-4 963 333 is provided at each incubator station 11. Such a cap is biased downwardly by a spring 10 against a support 14 for a slide test element E, for example, potentiometric slide elements available from Eastman Kodak Co. under the trademark "Ektachem"®. The cap has feet (or legs) 16 and 18 depending at opposite ends, the feet 16 being camming feet which cam the cap upward as a slide element E is inserted, in the direction of arrow 20. Under surface 22 between feet 16 and 18 acts to seal the surface of test element E against evaporation. (Additional details can be ascertained from US-A-4 963 333.) The solid line position of cap 12 is very satisfactory, provided the element E is inserted with the liquid drops adjacent the trailing edge (not shown). If instead, as is the case when a distributor (not shown) is used as described above, the projecting drops are adjacent the leading edge 24 as shown, then the solid line position of cap 12 is unsatisfactory as it contacts the drop(s). To avoid this, feet 16 would have to be extra large (shown in phantom) to cam the cap up to the position 12' shown. This is an unsatisfactory construct since, among other things, it holds surface 22 too far away to seal element E. Accordingly, in accordance with the present invention, the incubator is provided with caps and a cap-raising mechanism, as shown in Figures 2-5. Such an incubator comprises an annular test element support ring 30, Figure 3, on which is located a plurality of individual slide test element supports 32, each defining a station of the incubator. Each station has a width W and a length L as shown, for example, at support 32'. Supports 32 are recessed between guiding shoulders 34 and 36 used to locate a test element as it is inserted. Ring 30 is preferably mounted on bearings (not shown) and is rotated about axis 38, Figure 2, by means such as a drive gear 40 and its drive motor (not shown) which engages gear teeth 42 on the inner surface of ring 30. Each support 32 is separated from neighboring supports by intervening plates 44, Figure 3. These in turn are provided at 46, 48, and 50 with three apertures extending through ring 30. Apertures 48 and 50 are paired together along a radial direction R of ring 30, and are each offset lengthwise (in the direction of dimension L) from the position of aperture 46, to cooperate with the legs of the cap, discussed below. Loading and unloading of test elements E occurs via a platform 60, Figure 2, having guide rails 62 through which an element E is pushed, as indicated by arrow 64, to load the element on to one of the supports 32. To unload a finished element, that is, one already detected elsewhere by a conventional electrometer (not shown), a stationary ramp 66 is provided opposite to platform 60, and is attached, for example, to a dump chute 68 down which an ejected element E is pushed, as shown by arrow 70. The pushing is achieved by simply inserting a new slide test element E into, for example, station 32' to eject the "finished" slide test element E' on to ramp 66. Optionally, a guide roller 72 can be provided to control the amount of insertion of test elements, for example, element E'', as is described more fully in US-A-5 196 168. The evaporation caps 80 are provided as shown more clearly in Figures 3 to 5. More specifically, they comprise a body 81, Figure 4, having opposite ends 82 and 84, each of which has legs depending therefrom. Most specifically, end 82 has preferably a single leg 92, whereas end 84 has twin legs 94 and 96, offset from each other, and from leg 92, along the length L of each support 32, Figure 3. The position and size of each leg is such as to loosely extend through its respective aperture in plates 44, as shown in Figure 5. That is, leg 92 extends through aperture 46, Figure 3, leg 94 through aperture 50 (not shown) and leg 96 through aperture 48, so that legs 94, 96 (and their apertures) are on one side, and leg 92 and its aperture are on the other side, measured widthwise, of each support 32. Legs 92, 94 and 96 have sufficient length to project substantially below under surface 99 of ring 30, Figure 5. The end result is that legs 94 and 96 are located at the corners of end 84, whereas leg 92 is disposed in between the corners of end 82, and preferably, generally at the midpoint between those corners. Under surface 97 between leg 92, and legs 94, 96, Figure 4, acts to seal the drop-containing portion of elements E, using a hollowed-out recess as shown, for example, as described in US-A-4 963 333, Figure 2 (and in phantom as recess 52, Figure 3 herein). The relative position of each cap per its covered test element E'' is shown at support 32", Figure 3. To ensure that cap end 82 goes up and down substantially simultaneously with cap end 84, a cam 100, Figures 4 and 5, is provided, shaped to simultaneously raise (or lower) leg 92 at the time legs 94, 96 are raised (or lowered). To ensure nothing is in place above the caps 80 to obstruct access to the caps from above, cam 100 is disposed fixedly underneath ring 30 which rotates above it, in the direction indicated by arrow 102 in Figure 5. More specifically, cam 100 comprises a cam track 104, 106 and 108 for each of legs 94, 96 and 92, respectively, Figure 4. Because of the location of legs 92, 94 and 96, each track occupies a third of the overall surface of cam 100, with track 108 occupying the middle third. Each track also comprises a top land portion 110 and a root portion 112 which is below top land portion 110. Because legs 94 and 96 are radially aligned on ring 30, so are top land portions 110 for tracks 104 and 106. However, the onset of top land portion 110 for track 108, as well as the onset of its root portion 112, is spaced a distance circumferentially about axis 38, from the onset of the respective portions of tracks 104 and 106, which is effective to raise leg 92 (or lower it) at the same time that legs 94 and 96 are raised (or lowered). That spacing distance is of course the distance D between the leading edges 95 of a leg 92 and of paired legs 94, 96. As a result, as ring 30 moves (preferably, rotates) above cam 100, in the direction of arrow 102 in Figure 5, each cap is caused to raise and lower at the position at which platform 60 and ramp 66 are located, Figure 2, to allow loading and unloading of a test element, if needed. Because each end of the cap 80, arranged across the width W of each test element support 32 in the direction of travel of ring 30, goes up and down simultaneously as controlled by cam 100, the cap experiences substantially no sidewise thrust (across the width W of supports 32) and hence no significant sideways thrust is delivered to any test element underneath the cap. As used herein, "significant sideways thrust" means any such thrust which generates more than one gravitational force on the fluid mass on the test element. Thus, the two drops conventionally space-apart sideways on a potentiometric test element under the cap are not jolted towards each other such as could render the test inoperative. It is not essential that the single leg of end 82 be at the midpoint of that end. It can, for example, be at any location between the corners of that end, as shown in Figure 6. Parts similar to those previously described bear the same reference numeral, to which the distinguishing suffix "A" is appended. Thus, for the embodiment of Figure 6, leg 92A of cap 80A is radially (in the direction of R') closer to leg 94A than it is to 96A. Similarly, track 106A occupies almost half of the volume of cam 100A, and the other tracks 104A and 108A only 25% each, because of the location of the cap legs. The position of a test element E when sealed by cap 80A is shown in phantom.

Claims: An incubator comprising: - support means (30) for supporting a slide test element (E) in the incubator, the support means (30) including a plurality of stations (32) for supporting the test elements (E); first moving means (40, 42) for moving the support (30) about an axis (38); at least one evaporation cap (80) movable up and down relative to the support means (30) and located over a slide element (E) positioned thereon, the cap (80) having opposite ends (82, 84), and a sealing surface (97) between the ends (82, 84) to seal a slide element (E) against evaporation; and second moving means (100), disposed under the support means (30), for moving the cap (80) up and down relative to the support means (30); characterized in that the evaporation cap has at least one leg (92; 94, 96) depending from each end (82, 84) of the cap, the legs (92; 94, 96) extending through the support means (30) into contact with the second moving means (100); and in that second moving means (100) comprises a camming track (104, 106, 108, 110, 112) underneath the support means (30) for each of at least two different ones of the cap legs (92; 94, 96), the camming track (104, 106, 108, 110, 112) being shaped to move the cap legs (92; 94, 96) on each end of the cap (80) simultaneously up and down relative to the support means (30); whereby the first moving means (40, 42) provides relative movement between the support means (30) and the camming track (104, 106, 108, 110, 112), so that the cap (80) is raised and lowered without any significant, sideways thrust on it or on a test element (E) retained underneath the cap (80). An incubator according to claim 1, wherein each station (32) of the support means (30) includes through-holes (46, 48, 50), at least one of which is located on either side of the station (32) the holes (46, 48, 50) being the same in number and position as the legs (92; 94, 96) on the cap (80), the legs (92; 94, 96) projecting through the holes (46, 48, 50). An incubator according to claim 2, wherein the evaporation cap (80) has three legs (92, 94, 96) and the station (32) has three through-holes (46, 48, 50), two of the legs (94, 96) being located on one side of the station (32) with the other leg (92) on the other side of the station (32), the moving means providing movement in a direction in which the sides of the station (32) proceed sequentially. An incubator according to claim 3, wherein at least one leg (92) of the evaporation cap (80) is offset along the length (L) of the station (32) from the other legs (94, 96), the camming track (104, 106, 108, 110, 112) comprising at least two track portions (104, 106, 108) each lengthwise offset from the other(s) by a distance effective to ensure that only one of the legs (92, 94, 96) rides on each track portion (104, 106, 108), each track portion (104, 106, 108) further including a top land portion (110) and a root portion (112), the top land portions (110) and the root portions (112) of each track portion (104, 106, 108) being spaced a distance from the top land portions (110) and the root portions (112) of each of the other track portions (104, 106, 108) to ensure that the cap (80) is raised and lowered by the track portions (104, 106, 108) at each leg (92, 94, 96) simultaneously. An incubator according to claim 3, wherein the camming track (100) comprises three track portions (104, 106, 108) each forming a third of the camming track (100). An incubator according to claim 3, wherein the camming track comprises three track portions (104A, 106A, 108A), one of the track portions (106A) forming a half of the camming track with the other two track portions (104A, 108A) forming the other half of the camming track. An evaporation cap (80) adapted for use in the incubator of claim 1, the cap comprising:- a body portion (81) having a first end (82) and a second end (84); a sealing surface (97) extending between the first end (82) and the second end (84) for sealing over a test element (E) in which an analyte is to be detected; and a plurality of downwardly depending legs portions (92; 94, 96), the second end (84) having a pair of legs (94, 96) at its corners, the first end (82) having a leg (92) disposed to lie in between the corners of the first end (82). An evaporation cap according to claim 7, wherein the leg (92) at the first end (82) is disposed generally at the midpoint between the corners of the first end (82).

Inventors: MILLER JAMES GERARD, MILLER, JAMES GERARD, MILLER, JAMES GERARD, EASTMAN KODAK COMPANY
Applicants: JOHNSON & JOHNSON CLIN DIAG, JOHNSON & JOHNSON CLINICAL DIAGNOSTICS, INC.
Application year: 1994
Main classification: G01N35
IPC codes: C12M1, C12M3, G01N35